The art and popularity of wireless communications has grown significantly over recent years. Indeed, millions of people are engaging in voice and data communications using mobile stations such as cellular telephones and Personal Digital Assistants (PDAs).
In a typical cellular wireless network, an area is divided geographically into a number of coverage areas, such as cells and sectors, each defined by a radio frequency (RF) radiation pattern from a respective base transceiver station (BTS). Within each coverage area, the BTS's RF radiation pattern provides an air interface over which mobile stations may communicate with the cellular wireless network. In turn, the cellular wireless network may communicate with one or more other networks, such as the Public Switched Telephone Network (PSTN) or the Internet. As such, when a mobile station is positioned within a coverage area of the cellular wireless network, the mobile station can communicate with entities on the other networks via the cellular wireless network.
The RF air interface of any given coverage area in the cellular wireless network is typically divided into a plurality of channels for carrying communications between mobile stations and the cellular wireless network. For example, the RF air interface may include a plurality of forward-link channels, such as pilot channels, sync channels, paging channels, control channels, and forward-traffic channels, for carrying communications from the cellular wireless network to the mobile stations. As another example, the RF air interface may include a plurality of reverse-link channels, such as access channels and reverse-traffic channels, for carrying communications from the mobile stations to the cellular wireless network. However, the number of channels on a given air interface, and thus the number of simultaneous communications the given air interface can support, is limited by hardware and/or protocol constraints. As such, cellular wireless networks often try to conserve the limited supply of air-interface channels.
One common way a cellular wireless network conserves air-interface channels is by employing a paging process to locate idle mobile stations before assigning a traffic channel to those mobile stations. In this respect, when a given mobile station is idle, the cellular wireless network may only track the location of the mobile station at a coarse granularity (if at all), thus reducing the number of messages exchanged between the cellular wireless network and the idle mobile station. When the cellular wireless network receives a request to set up a communication with the given mobile station, the cellular wireless network may then page the given mobile station in a plurality of coverage areas, which may be selected based on a reference location such as a last-known location of the given mobile station. If the given mobile station is located in a given one of those coverage areas, the given mobile station may respond to the cellular network, and more particularly the BTS serving the given coverage area. Accordingly, the cellular wireless network may be able to locate the given mobile station without tying up traffic channels in various coverage areas or maintaining constant communication with the given mobile station.
Although the paging process described above may enable the cellular wireless network to conserve its limited supply of air-interface channels while locating mobile stations, the paging process may have a negative impact on call setup time. As such, an improved paging process is desired.